When it comes to Amazon vs. Walmart it’s hard to know who’s the angel and who’s the devil, but one thing we do know is that Walmart isn’t thrilled about its partners being on Amazon’s cloud. (Anyone else just get a Rolling Stones song stuck in their head?)

According to the Wall Street Journal, Walmart is telling some tech companies it works with that if they want to do business with Walmart, they can’t run applications on Amazon’s cloud-computing service. Guess Sam Walton doesn’t want Jeff Bezos pushing him further down the list of richest people in the world. (According to Forbes, Amazon’s purchase of Whole Foods earned Bezos $2.5 billion and cost the Walton family $7 billion.)

“It shouldn’t be a big surprise that there are cases in which we’d prefer our most sensitive data isn’t sitting on a competitor’s platform,” Walmart spokesman Dan Toporek told WSJ, noting that it only applied to a “small number” of tech companies that worked with Walmart.

Amazon accused Walmart of being a “bully” and said that it competes with retailers who use Amazon’s cloud services all the time. WSJ points out that Walmart’s efforts to curb Amazon cloud services aren’t likely to stop its growth, but it could boost rivals waiting in the wings.